Electromagnetic Spectrum: Generally, electromagnetic radiation is classified by wavelength into radio wave, microwave, terahertz (or sub-millimeter) radiation, infrared, the visible region is perceived as light, ultraviolet, X-rays and gamma rays.
Electromagnetic Wave: a wave produced by the acceleration of an electric charge and propagated by the periodic variation of intensities of, usually, perpendicular electric and magnetic fields
infrared: Of or relating to the range of invisible radiation wavelengths from about 750 nanometers, just longer than red in the visible spectrum, to 1 millimeter, on the border of the microwave region. Infrared light or the infrared part of the spectrum.
light year: the distance that light, which moves at a constant speed, travels in one year. One light-year is equivalent to 9.46 x 1015 meters, or 5,878 billion miles.
polarization:the direction in which it is oscillating. The simplest type of polarization is linear, transverse polarization.
ray: The notion of line or straight line was introduced by ancient mathematicians to represent straight objects with negligible width and depth. Lines are an idealization of such objects
ultraviolet: having a wavelength shorter than that of the violet end of the visible spectrum but longer than that of X-rays.
speed of light: The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its value is exactly 299,792,458 metres per second, a figure that is exact because the length of the metre is defined from this constant and the international standard for time.